If you write out the value of nullableDecimal to the console you will indeed see that it is 328.100 so I suppose technically, MbUnit is correct in claiming that the values aren't equal, although it sure looks like it's comparing string representations rather than actual values.

So in this case, my opinion is that NUnit handles things better because it allows you to use the variable in a more natural way. I.E. It doesn't shove in your face the fact that the variable is nullable.

Caveat: Don't take this as an endorsement for NUnit. The hillbilly still prefers MbUnit because he likes to pretend it stands for "Mountain boy unit".